• The Research Journal of the Costume Culture
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• v.24 no.6
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• pp.777-787
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• 2016

This study was carried out in order to provide useful data for planning fabrics of summer eco-friendly fashion products. The fabrics used in this study were four cellulose fibers: cotton, cotton/mulberry blended, flax, and flax/lyocell blended. Dyeing with natural indigo was carried out under three different reducing conditions (i.e., general, eclectic, and eco-friendly) that have different reducing agent and pH levels, and hydrosulfite and glucose were used as a reducing agent. The dye uptake (K/S value) of fabrics dyed with natural indigo by a reducing condition was the highest at 660nm. Regardless of the fabrics, dye uptake was the highest under the general reducing condition and the lowest under the eco-friendly reducing condition. Under different reducing conditions, the dye uptake of natural indigo fabrics with the maximum absorption wavelength indicated a difference. The colorfastness of cellulose fabrics that were dyed with natural indigo had a rate of 4 to 5 except for rubbing fastness, which indicated good colorfastness. Additionally, natural indigo-dyed cotton and flax fabrics had good antibiosis. When the color characteristics of fabrics dyed with natural indigo were measured, all of the three reducing conditions created purple blue (PB) colors, and the color characteristics of dyed fabrics by reducing condition and fabric showed significant differences.

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.3
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• pp.508-517
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• 2010

One-step reduction/dyeing method was optimized for wool dyeing with natural indigo dye in this study. The effects of reduction/dyeing conditions including dye temperature and time, the pH of bath, concentration of dye, and reducing agent on dye uptake and color were investigated. The dye uptake was higher with no addition of alkali. Dyeing was carried out through the use of only sodium hydrosulfite in the bath. The maximum dye uptake was obtained at $60^{\circ}C$ for 30min and the dyed fabrics appeared in the PB Munsell color range. Dye uptake improved with the increase of a natural indigo dye concentration with the same sodium hydrosulfite concentration. At a higher dye uptake, the fabric color became more purplish and the maximum absorption shifted from 660nm to 620nm. Color reproducibility was reliable with a color difference in the range of 0.41~1.43. Regardless of color strength, washing and dry cleaning fastnesses were good with a 4/5 rating, and fastnesses to rubbing and light were acceptable with a 3/4~4 rating.

• Journal of the Korean Society of Clothing and Textiles
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• v.40 no.6
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• pp.979-993
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• 2016

Mongolian cashmere sliver, yarn, and fabric were dyed and bleached with a solution of ascorbic acid and iron sulfate at $70^{\circ}C$, and then dyed using natural indigo powder at the dyeing temperature of $25^{\circ}C$ to $90^{\circ}C$ for 15-90 minutes using the IR dyeing machine. K/S values of bleached samples decreased significantly when dyed above $70^{\circ}C$ dyeing temperature for a longer dyeing time. Bleached cashmere fabric showed a greater loss of tensile strength than unbleached cashmere fabric, even when the samples were dyed at $40^{\circ}C$. With a higher dyeing temperature, yarns lost fullness, became thinner, and the pores between the yarns were enlarged. The x-ray diffraction pattern exhibited a prominent increase in crystallinity and the protein assay indicated a loss of protein in the bleached sample dyed at $90^{\circ}C$. Thinning of scales, fractured or raised tip of scales, and roughness on the entire surface of the fiber were also observed. The results indicate that bleaching and high temperature dyeing cause a serious damage to cashmere fibers. In addition, bleaching and high temperature dyeing cause significant fiber damage. Natural indigo dyeing using low temperature dyeing is recommended to produce blue color cashmere.

• Textile Coloration and Finishing
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• v.29 no.4
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• pp.276-283
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• 2017

The aim of this study is to develop an effective dyeing process for black color on the silk fabrics, using natural Indigo, Madder, Amur cork tree, Alder, Logwood, and Gallnut. All natural dye materials were water-extracted, concentrated, and freeze-dried. Seven different processes were carried out and the color differences(${\Delta}E$) of black color with each process from the chemical black dyed fabric were compared. The light, washing, and rubbing fastness were evaluated. The black dyeing of the silk fabrics was well carried and excellent black color was obtained in every methods. The profound black color could be obtained by the subtractive mixture of the three primary colors of red, yellow, and blue in the order of indigo(blue) - amur cork tree(yellow) - madder or lac(red). Black color was efficiently obtained by iron mordant when logwood or alder fruit was used. The color difference(${\Delta}E$) from the black color with chemical dyestuff was the lowest in the indigo - amur cork tree - lac - iron method. Light fastness and washing fastness were excellent in all dyeing processes, showing grade 5. The fastness to rubbing was excellent as shown grade 5 in the dry samples of logwood - iron process and alder fruit - iron process.

• Journal of Sericultural and Entomological Science
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• v.44 no.2
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• pp.93-98
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• 2002

Effect of reducing agent sodium hydrosulfite on the natural indigo on the silk fabrics were examined to improve traditional dyeing method. K/S values of dyed fabrics was monitored with various dyeing temperature time, amount of dye and reducing agent. The dyeability of silk fabrics was improved by using reducing agent, sodium hydrosulfite; K/S value (7.20) was higher then that (1.09) of traditional method at the frist dyeing. Natural indigo dye extracted from dyed silk fabrics are composed of isomer, indigo (67.3%) and indirubin (32.5%). However, silk fabrics showed excellent anti-microbial activity regardless of the dyeing methods.

• Fashion & Textile Research Journal
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• v.13 no.2
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• pp.263-268
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• 2011

One-step reduction/dyeing method was applied for ramie dyeing with natural indigo powder. The effect of reduction/dyeing conditions including the pH of bath, dye temperature and time, and concentration of indigo powder and reduction agent on dye uptake and color properties were investigated. Regardless of addition of alkali, the dyed fabrics appeared in the PB Munsell color range(${\lambda}_{max}$: 660 nm) and the dye uptake was much higher with no addition of sodium hydroxide. Dyeing was carried out through the use of only sodium hydrosulfite in the bath. The maximum dye uptake was obtained at 60 for 30min. Saturated dye uptake was obtained at 2 g/L of sodium hydrosulfite concentration up to 2 g/ L of indigo powder. Whereas, at higher indigo powder concentration (4 g/L), more than 3 g/L of reducing agent concentration was required for obtaining the saturated dye uptake. Color reproducibility was reliable with color difference in the range of 0.03~0.16. Regardless of color strength, fastness to rubbing was acceptable with a 3/4~4/5. Fastness to washing, dry cleaning, and light of samples with low color strength were poor. Whereas, fastness to washing, dry cleaning, and light of samples with high color strength were very good.

• Textile Coloration and Finishing
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• v.16 no.5
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• pp.19-27
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• 2004

The dyeing on cellulose fibers such as cotton and viscose viscose rayon was carried out by the use of solution extracted from natural fresh leaves of indigo plant under several dyeing conditions. The dyeing affinity of viscose rayon was higher than that of cotton. The total K/S value of dyed fabrics was considerably increased with repeated dyeings, while a dyeing time has a little influence on it. Both fibers were hardly dyed by indigo at $60^{\circ)$ and cotton was dyed better at $40^{\circ)$ than at $20^{\circ)$, but in viscose rayon, a little difference of total K/S was shown between $20^{\circ)$ and $40^{\circ)$. The color change of dyed fabric according to dyeing conditions was evaluated by the CIELAB color system. viscose rayon had a lower $b^*$ so that it looked bluer than cotton and when the celluose fibers were dyed by indigo plant at the lower temperature, the bluer it looked. By repeated dyeings the $b^*$value of dyed fabrics was much increased but the $a^*$ value was little influenced and in case of viscose rayon the change was considerable.

• Science of Emotion and Sensibility
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• v.20 no.3
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• pp.3-12
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• 2017

This research was carried out in order to suggest useful data for planning fabrics of summer eco-friendly fashion products. For this purpose, four cellulose fabrics were dyed with natural indigo under three different dyeing conditions, then, their colorimetric properties and color sensibilities were evaluated, and their influences on color preferences were analyzed. All cellulose fabrics naturally dyed with indigo showed the characteristics of PB color tones, middle and low value, and low chroma. Color characteristics were significantly different according to fiber type and dyeing condition. The color sensibilities of the fabrics dyed with indigo were classified into three factors: sporty, classic and natural. These sensibilities showed partially significant differences according to fiber type and dyeing condition. Also, there were partially significant relationships between color characteristics and the color sensibilities of the fabrics dyed with indigo. The color preferences of the dyed fabrics with indigo were found to be influenced by the sporty and classic of color sensibility and $L^*$ of color characteristics.

• Textile Coloration and Finishing
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• v.21 no.2
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• pp.29-39
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• 2009

The color mixture, obtained from Indigo and Japanese pagoda tree, was applied to cellulose fibers such as cotton, linen and rayon to diversify color gamut of natural dyes. The color mixture was tried with two different methods. The first process was that cellulose fibers were dyed with $5{\sim}25%$ owf Japanese pagoda tree solution, and then dyed 1 to 4 times with Indigo. The second process was dyeing 1 to 7 times with Indigo, followed by dyeing with $5{\sim}25%$ owf Japanese pagoda tree solution. K/S value of the dyed fibers with one colorant and color mixture increased in the order of linen, cotton, rayon. It was also found that the first process could give higher K/S values than the second process.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2008.04a
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• pp.102-104
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• 2008

Natural indigo dye was prepared by extracting from Polygonum tintorium, precipitating with calcium hydroxide, and dried. Dyeing was carried out using sodium hydrosulfite as a reducing agent for the prepared natural indigo powder. K/S value, color property, and colorfastness of dyed fabrics were investigated. Optimum dyeing conditions obtained were 60$^{\circ}C$, 20min. Regardless of indigo dye and sodium hydrosulfite concentration, Munsell hue of dyed fabrics was PB color. Compared to the dyed fabric with both sodium hydroxide and sodium hydrosulfite, those with sodium hydrosulfite only showed higher color strength(K/S value). Colorfastness of dyed fabrics showed high rating except of wash/dry cleaning fastness of silk fabrics dyed low color strength.